1. Field of the Invention
The present invention relates to a GPS (global positioning system) receiving antenna for cellular phone, and more particularly, to specially constructed L-shaped, Y-shaped, and U-shaped receiving antennas for cellular phone capable of most effectively abstracting energy of the radio wave from the satellite, and the above-mentioned antennas can be fabricated easily with a reduced production cost.
2. Description of the Prior Art
According to USE-911 regulations, the cellular phone is obligated to have positioning function, and one of the most well-known positioning system is GPS wherein a cellular phone is equipped with a receiving antenna capable of receiving radio wave signals radiated from the satellite.
For smoothly receiving radio wave signals, a receiving antenna has to bring into consideration the following factors:                1. The wavelength of the received radio signal is about 20 cm. If a ¼ wavelength antenna is to be used, the required length is 5 cm.        2. The capturing pattern of the receiving antenna should be upwardly directed to the sky for abstracting energy of the radio wave from the satellite so as to eliminate any possible dead angle.        3. In view of the fact that the field distribution under the satellite transmitting antenna is in a clockwise circular polarization pattern, the receiving antenna shall be configurated to match this pattern so as to effectively abstract energy of the radio wave radiated from the satellite antenna. Should the antenna be configurated to match the linear polarization, the receivable wave energy will be halved. As it is well known, the radio wave energy radiated from the satellite antenna is very weak, so that using an unmatched receiving antenna for the cellular phone may result in failing to catch the coming signal successfully.        Accordingly, for a remedy to afore-mentioned defect, a high dielectric constant ceramic material is employed to form into a patch-receiving antenna for the cellular phone. In fact, the configuration of a patch antenna is suitable for upwardly directing to capture the circularly polarized clockwise spinning radio wave. In addition, the driftage of the received signals never happens to the receiving patch antenna because the ceramic is insensitive to temperature variation.        There are several types of patch antenna that have been used for the cellular phone as shown in FIG. 1a and FIG. 1b.         Referring to FIG. 1a, the receiving antenna is equipped on the rear housing surface of the phone. It is advantageous that the gain of the receiving antenna will be considerably high due to both large antenna size and grounding area thereof, and can be fabricated with a simple process. However, by equipping the receiving antenna only on the rear housing surface of the phone causes acceptable radio wave energy radiated from the satellite to be limited to that arriving at the rear housing surface only and leaving the front housing surface dummy. Although the top portion of the antenna facing to the satellite can receive the linearly polarized signals, yet the effect is not significant.        Referring to FIG. 1b, the receiving antenna is equipped on a part of top housing surface of the cellular phone. By doing so, unmatching problem as that mentioned in the above example is solved by abstracting polarized radio wave energy downwardly radiated from the satellite. However, a material of very high dielectric property must be selected to construct the receiving antenna which is deemed to be equipped on so narrow top surface area that having a width less than 10 mm. As a result, the antenna power loss is increased, and its gain is reduced. Besides, a highly precise technology is required for fabricating such a small-sized antenna that results in a poor yield.        Aiming at the above-depicted defects, the present invention is to propose a newly developed GPS receiving antenna for cellular phone capable of rectifying the above depicted defects and operating effectively and sensitively to receive the radio signal from the satellite.        